Hello, Tom, good to meet a fellow 58XXX owner! I hate to say, I don't know if they're aluminum or stainless; if I had to guess, I'd say stainless. I bought a replacement strip on eBay, for the short piece below the taillight, but I was able to fix the old one instead, so I kept it on. The unused eBay one appears to be stainless as well; it has this #: 554172, which corresponds to Wing Bead Assembly, Rear (short). It has the same look as all my other beading, but you're right. These tabs are 2 inches long, which is much longer than I remember the original tabs being. So now I don't know how to answer your question, but I'm sure it's all the original beading. If you can tell the difference, please let me know!